Magnetic reed switch



Dec. 24, 1968 J. s. HAMMOND 3,4133;10

MAGNETIC REED SWITCH Filed Aug. 26, 1966 2 Sheets-Sheet l INVENTOR. JOHN S. HAMMOND Dec. 24, 1968 I J. s. HAMMOND 3,418,610

MAGNETIC REED SWITCH Filed Aug. 26, 1966 2 Sheets-Sheet 2 15, I; INVENTOR. am" I? JOHN S. HAMMOND United States Patent 3,418,610 MAGNETIC REED SWITCH John S. Hammond, 34 Lincoln Ave, Greenwich, Conn. 06830 Filed Aug. 26, 1966, Ser. No. 575,382 4 Claims. (Cl. 335-205) ABSTRACT OF THE DISCLOSURE A self contained magnetically operated reed switch in which the magnet for operating the switch and a vane for shunting the magnetic flux so as to prevent operation of the switch are mounted for rotary motion in the same housing as the reed switch and adjacent to it.

This invention relates to magnetically actuated reed switches and more particularly to such switches wherein the magnetic actuating element is a part of the switch assembly.

A reed switch comprises generally a pair of movable reed contacts within a hermetically sealed capsule. The contacts are caused to engage by a magnetic force, usually supplied by a permanent magnet, brought into proximity with the switch. Removal of the magnetic force permits the switch contacts to separate. Because such switches are sensitive to small actuating forces, operate at high switching rates, and are accurate over the life of a switch in that operations are repeated when the actuating force is restored to the precise operating point, plus or minus a very small distance tolerance, reed switches find many applications as limit switches in instrument and control circuits.

It is the object of the present invention to provide improved reed switch assemblies whereby utilization of the switch in limit switch and high speed precision switching arrangements is enhanced.

In carrying out the invention, the permanent magnet that provides the actuating force for the reed switch contacts is made a permanent part of the switch assembly, and its position relative to the switch contacts is varied depending on the control to be exercised. Thus in one embodiment the permanent magnet is mounted on a pivotable lever and can be moved towards and away from the reed contacts to effect their engagement and separation by cams, plungers, slides, rollers or the like. In another embodiment the permanent magnet is mounted directly in the switch housing but is separated from the reed contacts by a ferrous vane that shunts the magnetic lines of force and prevents the reed contacts from responding to the proximate magnet; by rotating the vane into and out of its shunting position, control over operation of the switch is obtained.

Features and advantages of the invention may be gained from the foregoing and from the description of a preferred embodiment thereof in the following specification taken in conjunction with the accompanying drawings.

In the drawings:

FIG. 1 is a front elevational view of one half of the switch housing;

FIG. 2 is a sectional view taken along line 22 of FIG. 1;

FIG. 3 is a view showing a hermetically sealed reed switch connected to two terminal pins;

FIG. 4 is a view showing the reed switch and terminal pins mounted in the housing shell of FIG. 1;

FIG. 5 is a view showing an assembled switch with its actuating magnet;

FIG. 6 is a fragmentary view of an assembled switch showing a different arrangement of the magnet lever;

FIG. 7 is a fragmentary view of an assembled switch showing an arrangement for varying the position of the actuating magnet;

FIG. 8 is a sectional view taken along line 88 of FIG. 7;

FIG. 9 is a view similar to FIG. 3 but showing the actuating magnet mounted in the switch housing;

FIG. 10 is a view similar to FIG. 5 but showing the magnet lever mounted for vertical rotary motion;

FIG. 11 is an end view of the switch assembly of FIG. 10;

FIG. 12 is a view similar to FIG. 10 but showing the magnet lever mounted for horizontal rotary motion;

FIG. 13 is an end view of the switch assembly of FIG. 12;

FIG. 14 is a schematic representation of a rotary switch having a plurality of switch housings and a single rotating magnet lever;

FIG. 15 is a schematic representation of a switch of the type shown in FIG. 9 actuated by a rotating disk of alternate ferrous and non-ferrous segments;

FIG. 16 is an elevational view of a switch housing having a rotatable magnet member mounted therein;

FIG. 17 is a sectional view taken along line 17-17 of FIG. 16; and

FIG. 18 is a view similar to FIG. 17 but showing a multiple switch assembly.

Referring now to FIG. 1, there is shown one half of a switch housing 20. The housing preferably is molded of Bakelite or any other suitable insulating material, and is formed with a central cavity 21 which can accommodate the reed switch to be placed in the housing. A rim comprising an end wall 22, a top segment 23, and another end wall 24, and a wider base portion 25 surround central cavity 21. A pair of bosses 26 are formed on the base portion, and are provided with openings 27 through which screws or eyelets can pass to hold two housing segments together.

The base portion 25 of the housing is also provided with two identations 30 which will hold the terminal pins of the reed switch proper. Each indentation is formed with an upper 31 and a lower 32 half cylindrical depression joined by a similar depression 33 of smaller diameter. The arrangement is such that when two housings 20 are joined together to form a complete switch housing as with eyelets or screws as above mentioned or with a suitable adhesive, each indentation will securely hold a terminal pin. Of course, further indentations can be provided if required as for a single pole double throw reed switch.

A rib 34 is molded in cavity 21 to strengthen the housing when two of them are secured together in assembling a switch. The rib also forms a channel 35 between it and top wall 23 into which a reed switch can be firmly placed. In this way the position of the reed switch can be maintained with respect to the actuating magnet which will be brought into proximity with the switch.

Turning now to FIG. 3, a reed switch 36 of conventional construction is shown. The switch is a single pole single throw switch having two normally separated reed contacts. Connecting leads 37 and 38 are brought out of the ends of the hermetically sealed capsule 40 that encloses the reed contacts. The connecting leads are shown electrically connected to terminal pins 41 and 42. These pinsare formed to fit into the indentations 30 provided in housing 20. Indent-ations and terminal pins of other shapes could be provided, but that shown has been found to be quite satisfactory. If the connecting leads 37 and 38 are relatively substantial in cross-section a fairly rigid structure can be formed which is easily handled and assembled into housing 20. See FIG. 4.

In FIG. 5, a complete switch assembly is shown. It comprises an assembled switch according to FIG. 4 with a second housing member 20 secured over reed switch 36 and terminal pins 41 and 42. A lever supporting member 43 is secured to the housing by eyelets 44 which pass through the elongated slots 45 punched in the lower arm 46 of member 43. The elongated slots allow member 43 to be adjusted vertically; in this way the air gap between the actuating magnet and the reed switch within the switch housing can be accurately controlled. By setting the magnet close to the switch, but not quite close enough to cause its actuation, a switch sensitive to very small movements can be provided.

The vertical arm 47 of member 43 is at its upper extremity bent into a hook shaped end that supports a pin 50. The pin in turn rotatably supports a non-ferrous lever 51 which is bent around the pin and is urged against the stop arm 52 of member 43 by a compression spring 53. The spring 53 is maintained in place by being set in a small depression formed in the top wall of housin 20 and fitted over a small tit punched in lever 51.

A permanent magnet 54 is secured to lever 51. The arrangement is such that the reed switch mounted within housing 20 is normally non-actuated but when lever 51 is pivoted counterclockwise as shown in FIG. the reed switch will be actuated when the air gap between the magnet 54 and the switch is reduced to that determined by the switch and the strength of the magnet used.

While not shown, the lever 51 can be extended beyond pin 50 and a weight hung thereon. In this way the force required to act on lever 51 can be calibrated in the manner of a beam scale.

Rather than have a fixed stop arm for lever 51 as shown by reference numeral 52 in FIG. 5, an adjustable abutment can be provided as in FIG. 6. Here the stop member is seen to be a screw 55 which is adjustably threaded through the extension 56 of arm 47. This provides a simple and readily adjusted means for controlling the normal air gap of the switch.

FIGS. 7 and 8 show a modified arrangement of the magnet lever. In this embodiment, the lever 57 is formed to provide a channel shaped course in which the permanent magnet 54 is placed. However, the side walls 60 and 61 are tapered towards each other so that the magnet is firmly grasped therebetween and does not have to be secured to the lever as by adhesives. Now it is very easy to adjust the position of the magnet longitudinally with respect to the lever and, of course, the reed switch mounted within housing 20. In this way switches of identical operating characteristics can be provided even though the reed switches themselves have different air gaps and hence different operating characteristics or even though the reed switch position within the housing is slightly altered as by connecting leads 37 and 38 being bent while assembling the switch.

In the switches so far described, the switch contacts are normally separated and are brought into engagement when the magnet is pivoted towards the switch. In FIG. 9, the arrangement is such that the reed switch contacts are normally biased into engagement. In the figure, the reference characters have the same significance as they had in the de-.

scription of the earlier figures of the drawings. In this embodiment, the permanent magnet 62 is shown mounted directly within housing 20 so that its magnetic force is always acting on the reed contacts to bring them into engagement. In this case the lever 63 becomes a ferrous member which when pivoted into proximity to the reed switch acts as a shunt for some of the lines of force emanating from the magnet thus permitting the reed contacts to separate. When the lever is restored to its position against stop 52, the magnet 62 again causes the reed contacts to engage in the fashion of a normally closed switch. The magnet may be a ceramic magnet so that the action of its field of force may be accurately controlled.

FIGS. 10 and 11 show a switch arrangement similar to that shown in FIG. 5 except that the lever 51 is secured to shaft 64 and is rotatable therewith. The shaft is supported for rotation in journal block 65 formed on switch housing 20. In this embodiment rotary motion imparted to shaft 64 can be converted to switch operations without any physical engagement of parts thus assuring repeatable operations over long periods of use. FIGS. 12 and 13 similarly show an arrangement whereby the magnet lever 51 rotates about a vertical axis. Here again, a boss 66 supports the lever for rotation and the shaft 67 can be driven by any suitable means. While the embodiments shown in FIGS. 10 to 13 illustrate a normally open reed switch actuated by a magnet carried by a rotating lever, the switches could just as well have been normally closed reed switches of the type shown in FIG. 9 in which case the rotating lever would have been of a ferrous material.

FIG. 14 schematically represents :a rotary switch in which lever 52 carrying magnet 54 is rotated past circumferentially arranged switches 70. Lever 51 can be rotated continuously in which case switches 70 are sequentially actuated at a rate depending on the speed of rotation, or lever 51 can be stepped by a ratchet wheel device in which case the arrangement shown in FIG. 14 becomes a stepping switch. An alloy wire 69 having the same diameter as the reed switch contacts is placed in :a loop beneath the switches. With such an arrangement, the magnet force applied to the reed switch contacts is relatively constant so that the differential operating position of the magnet with respect to a pair of reed contacts is rather narrow and precisely defined. The wire loop may be segmented and extend between the switches 70 rather than form a continuous loop.

FIG. 15 schematically illustrates another arrangement in which switch 71 is of the type shown in FIG. 9 and a disk 72 having segments 73 of ferrous materal alternating with segments 74 of non-ferrous material. Thus, as disk 72 is rotated the reed contacts of switch 71 are alternately separated and engaged.

In FIG. 16 a further embodiment of the invention is shown. Here the switch housing is provided with a bore 75 that accepts a magnet cylinder 76. The cylinder is of an insulating material such as Bakelite and has the permanent magnet 77 and a ferrous vane 78 molded therein.

With the magnet 77 and vane 78 positioned as shown in FIGS. 16 and 17, the contacts of reed switch 80 will be separated because the vane 78 shunts part of the magnetic lines of force from magnet 77 away from switch 80. However, if cylinder 76 is rotated degrees clockwise (FIG. 17) vane 78 will no longer shield switch 80 and the contacts therefore will engage. Returning the cylinder to the position shown in FIGS. 16 and 17 will again cause the reed contacts to separate.

Rotation of cylinder 76 may be had by forming a helical thread on cylinder 76 and a corresponding threaded bore in housing 20, in which case rotation of the cylinder would result from a longitudinal axial force applied to the cylinder. A spring (not shown) could restore the cylinder to its normal position. Alternatively a rotary motion could be applied to the end of cylinder 76 protruding from housing 20. Cylinder 76 could be provided with key notches in which case the cylinder could be inserted and rotated only if notched correctly. Thus it is clear that any combination of longitudinal and rotary motion may be used to actuate the switch.

More than one vane can be molded into cylinder 76 so that a close-open-close-open operation of switch 80 can be obtained in one revolution of cylinder 76. This assumes that a second vane will be located diametrically opposite vane 78. By locating the second (or third, etc.) vane in different locations, a different sequence of switch operations can be effected.

If more than one pair of switch contacts are required for a particular operation, the arrangement shown in FIG.

18 may be employed. Here four reed switches 81, 82, 83, and 84 are illustrated. In the embodiment shown, switch 81 will be non-actuated and switches 82, 83, and 84 will be actuated. As cylinder 85 rotates clockwise, the non-actuated will become in sequence, switch 82, switch 83, etc. By a suitable arrangement of vanes 86 which will suggest itself from the present disclosure, any desired arrangement of switch operations may be had. For example, by placing a second vane on the opposite side of magnet 86 from vane 85, the contacts of switches 81 and 82 (and '83 and 84) can operate as the normally separated and the normally engaged contacts of a relay. And each quarter turn of cylinder 87 would correspond to the energization followed by the deenergization of the relay.

Having thus described the invention it is to be understood that many embodiments thereof will suggest themselves without departing from the spirit and scope of the invention. Therefore, it is intended that the specification and drawings be interpreted as illustrative rather than in a limiting sense.

What is claimed is:

1. A magnetic reed switch assembly comprising a plurality of switch housings, a reed switch mounted within each of said switch housings, a magnetic actuator mounted for movement past said reed switches to cause said switches to be sequentially actuated, and a ferrous magnetic conductor having the same magnetic characteristics as the reed switch contacts, said conductor extending between the switch housings along the path traversed by said magnetic actuator.

2. A mechanically actuated switch comprising a switch housing, a reed switch mounted within said housing, a cylinder-like member mounted for rotary motion in said housing adjacent said reed switch, a magnetic actuator carried by said member, and a ferro-magnetic actuator carried by said member, the arrangement being such that when said cylinder-like member is rotated the ferro-magnetic actuator moves between a position wherein it shunts the magnetic lines of force from said magnetic actuator so that said reed switch is not actuated and a position wherein the reed switch is actuated by said magnetic actuator.

3. A mechanically actuated switch according to claim 2 including at least a second reed switch mounted in the switch housing.

4. A mechanically actuated switch according ot claim 3 including a second ferro-magnetic actuator mounted in the cylinder-like member.

References Cited UNITED STATES PATENTS 2,648,234 8/1953 Lester 200-153 X 3,164,696 1/1965 Pusch 335153 X 3,201,537 8/1965 Klatte et al. 335153 X 3,205,323 9/1965 Deshautreaux 335l53 X 3,260,820 7/1966 OBrien 335-453 BERNARD A. GILHEANY, Primary Examiner. R. N. ENVALL, JR., Assistant Examiner.

.U.S. Cl. X.R. 200-47; 335206 

